What is the maximum amount of moles of P2O5 that can theoretically be made from 136 g of P4 and excess oxygen

We are given with

136 g P4

excess oxygen

The complete combustion reaction is

P4 + 5O2 = > 2P2O5

Converting the amount of P4 to moles

136/123.9 = 1.098 moles

Using stoichiometry

moles P2O5 = 1.098 x 2 = 2.195 moles P2O5